Lofting complex geometry from wire frame

[vcientanni]

Hey there, I've had a search on the forums to answer my problem; but I'm extremely new to Fusion 360 and I don't understand what I'm doing! I want to model a complex shape from some scale drawings I did (see attached). I've built a basic wire frame (took me all day to draw in 3D!) and now I want to fill this wire frame as a volume. I've been trying to use the loft tool for this; but I just can't get it to loft along the wire frame as rails. I think I need more rails? Or to divide the shape up more? Perhaps I need to do this in a completely different way (such as using the form tools, but I find that equally as time consuming and produces a not so accurate/simple geometry). It takes SO long to add lines and I can just tell I'm doing this in a terrible way (I can never seem to get my sketches to stay in a construction plane, or to snap to already built sketches/rails). Some advice or help would be much appreciated!  

[TheCADWhisperer]

What are you attempting to model?

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

[g-andresen]

Hi,

If you would show an image of a real existing object it would be easier to say something about it.

For example if a wireframe is necessary or useful at all.

Günther

[davebYYPCU]

We need your file to make constructive comment.  File > Export save to hard drive, 

Stick to 2d planar sketches.

Less spline points is better than a higher number.

Sketches should be fully constrained, (splines excepted)

Yellow timeline icons should be fixed when they occur with Undo.

Loft has procedures to follow or you end up frustrated.

Loft rails, must connect to all profiles, 

Loft rails of multi segments, need to have tangent connections, where Profile do no have that restriction.

Might help....

[vcientanni]

Thank you all for such prompt replies, and my apologies for not including this in the first instance! Please note the canvases I've used aren't fully updated (so you may note I haven't drawn to them exactly in the orthographic views), it is however still the same approximate shape (minus maybe 5 mm)

[davebYYPCU · Accepted solution]

You are on the right track.  Because the fuse is creased, you can only build the faces as separate Surface Lofts.

All your rails are connected, well done.

Two edits needed, there was no tangent connection on the rear profile at the top connection, and

the lower ellipse has to be broken into segments, 

Four lofts, to get this far. do half and mirror.

Might help....

[davebYYPCU]

[vcientanni]

Thank you very much daveb - your file was invaluable in helping understand how to perform these surface lofts! Some notes:

- I revised the design a little to better make use of the constraints you outlined earlier

- I followed your solution here: https://forums.autodesk.com/t5/fusion-360-design-validate/is-there-a-command-option-to-flip-invert-a... for flipping surface normals to create a properly bounded surface

- One of my (many, many...) mistakes was attempting to use the 'solid' loft rather than surface loft piece by piece. I was attempting to essentially loft the entire geometry all at once!

The result now: 

Thank you again!

[davebYYPCU]

When you have the half model lofted, 

Stitch those to become a single body,

(stitching will fix the normals - gold sides are - insides in the strictest sense - my bad - as I wanted the pic contrast)

This eliminates the (so) many Mirror commands.

By that I mean, stitch the front lofts then address the rear fuse, half wing and half tail, then mirror.

After the mirror, and last stitch you should arrive at solid body/s.

Construction of the model should be driven by the desired output required from fusion.

Might help....